EPrinter Exception

Hi
    I have a very strange EPrinter exception being thrown at program
initialization time.
An app (written in delphi 4 std)  that was fine before has all of a sudden
begun throwing EPrinter exception saying "selected printer is not valid". If
I delete all of the printers on the system it stops happening If I
re-install a network printer this EPrinter happens again. This is really
baffling as
my other apps work just fine on the same computers. I have tested this
behaviour on several
machines and have found that this happens on all of them. I am lost in terms
of what to do next.
Any help greatly appreciated.

Thanks in advance
Jarek Bialik